HackerRank - Making Candies

class Result {

    /*
     * Complete the 'minimumPasses' function below.
     *
     * The function is expected to return a LONG_INTEGER.
     * The function accepts following parameters:
     *  1. LONG_INTEGER m
     *  2. LONG_INTEGER w
     *  3. LONG_INTEGER p
     *  4. LONG_INTEGER n
     */

    public static long minimumPasses(long m, long w, long p, long n) {
    // Write your code here
        long candies = 0;
        long turns = 0;
        long minDays = calculateDays(m, w, n);
        long turnsToBuy = calculateDays(m, w, p);
        while (minDays - turnsToBuy > 1) {
            turns += turnsToBuy;
            minDays -= turnsToBuy;
            candies += turnsToBuy * m * w;
            long newMW = candies / p;
            candies %= p;
            if (m < w) {
                long diff = w - m;
                if (diff >= newMW) {
                    m += newMW;
                } else {
                    newMW -= diff;
                    m += diff  + (newMW % 2 == 0 ? newMW / 2 : newMW / 2 + 1);
                    w += newMW / 2;
                }
            } else if (w < m) {
                long diff = m - w;
                if (diff >= newMW) {
                    w += newMW;
                } else {
                    newMW -= diff;
                    w += diff  + (newMW % 2 == 0 ? newMW / 2 : newMW / 2 + 1);
                    m += newMW / 2;
                }
            } else {
                m += newMW % 2 == 0 ? newMW / 2 : newMW / 2 + 1;
                w += newMW / 2;
            }
            long days = calculateDays(m, w, n - candies);
            if (minDays < days) {
                break;
            }
            minDays = days;
            turnsToBuy = calculateDays(m, w, p - candies);
        }
        return minDays + turns;
    }
    
    static long calculateDays(long m, long w, long n) {
        try {
            long prod = Math.multiplyExact(m, w);
            return n % prod > 0 ? n / prod + 1 : n / prod;
        } catch(ArithmeticException ignore) {
            return 1;
        }
    }

}